1. Field of the Invention
The invention relates to a nose cover for a dome, through which radiation can pass, for a missile.
In the case of missiles, particularly in the case of guided missiles which respond to infrared radiation, the nose of the missile is formed by a dome through which radiation can pass. Search-head optics and a detector which is sensitive to radiation and by means of which the missile can detect targets are arranged behind the dome, in the interior of the missile. A dome such as this is typically spherical. This is due on the one hand to the fact that hemispherical—that is to say spherical—domes can be produced relatively easily and accurately, and on the other hand to the fact that, when the search-head optics are being scanned about the centre of curvature of the dome, there are no influences that are dependent on the position of the search-head optics on the beam path striking the dome, after the beam has passed through the dome. The optical effect of a spherical or hemispherical dome is thus always the same even when the alignment of the search-head optics changes. A spherical dome thus offers the capability to scan observation areas as far as the hemisphere boundaries without any adverse effects on the imaging.
2. Discussion of the Prior Art
However, spherical domes have comparatively high aerodynamic drag. Conformal optics are known from the article “Precision Conformal Optics Technology Program” by Patrick A. Trotta (which appeared in the Proceedings of SPIE, Window and Dome Technologies and Materials VII, Volume 4375, April 2001). These conformal optics are optics which do not have the conventional—that is to say spherical—shape, in order to reduce the aerodynamic drag of missiles. A conformal dome therefore produces less drag than a spherical dome, hence increasing the speed of the missile and/or its range. However, in contrast to a hemispherical dome, the optical effect of a conformal dome is dependent on the alignment of the search-head optics. It is no longer possible to cover a hemispherical observation area. In order to overcome this problem, correction optics are provided which make it possible to enlarge the field of a view, which is constricted by the conformal dome. However, correction optics can overcome this defect only in a very restricted range.
As a consequence of this, all that is possible is to produce missiles which either achieve only a low speed because of their spherical dome, or have a short range owing to their spherical dome, but which allow scanning of a hemispherical observation area, or which achieve a high speed and have a long range owing to their conformal dome, but which allow only a restricted field of view to be scanned.